331:, therefore 24 bits fully describe the color of each pixel. The full system palette for such hardware therefore has 2 colors. The objective of the usage of smaller palettes via CLUTs is to lower the number of bits per pixel by reducing the set of possible colors that are to be handled at once (often using adaptive methods). Each possible color is assigned an index, which allows each color to be referenced using less information than needed to fully describe the color. An example is the 256-color palette commonly used in the
299:'s color reproduction range are assigned an index, by which they can be referenced. By referencing the colors via an index, which takes less information than needed to describe the actual colors in the color space, this technique aims to reduce data usage, including processing, transfer bandwidth, RAM usage, and storage. Images in which colors are indicated by references to a CLUT are called
33:
268:
743:
system applies an internal algorithm to discard the least-used color in the system palette (generally, one used by another window in the background) and substitutes it with the new color. Due to there being limited room for colors in the system palette, the algorithm also tries to remap similar colors together and will always avoid creating redundant colors.
756:
those hardware palette entries no longer are free for its palette color management algorithm. The final result depends on the skills of the color-forcing program and the behavior of the other programs (although this problem is the same as in the regular case), and that of the operating system itself.
755:
An application can force the system palette to be loaded with specific colors (even in a specific order), "tricking" the system by telling it they are color entries intended for animation (quick color changes of the colors in the physical palette at specific entries). The system will then assume that
742:
its logical palette: The system tries to match the "logical" colors with "physical" ones. If an intended color is already present in the system palette, the system internally maps the logical to the system palette indexes (because they rarely coincide). If the intended color is not present yet, the
746:
The final result depends on how many applications are trying to show their colors on screen at the same time. The foreground window is always favored, so background windows may behave in different ways: from become corrupted to quickly redraw themselves. When the system palette changes, the system
424:
Then, when loading the mosaic of image thumbnails (or other heterogeneous images), the program simply maps every original indexed color pixel to its most approximated in the master palette (after dumping this into the hardware color registers), and writes the result in the video buffer. Here is a
734:
When a given application intends to output colorized graphics and/or images, it can set their own "logical palette", that is, its own private selection of colors (up to 256). It is supposed that every graphic element that the application tries to show on screen employs the colors of its logical
335:
file format, in which 256 colors to be used to represent an image are selected from the whole 24 bit color space, each being assigned an 8 bit index. This way, while the system can potentially reproduce any color in the RGB color space (as long as the 256 color restriction allows), the storage
751:
to inform every application. When received, a window can quickly redraw itself using a single Win32 API function. But this must be done explicitly in the program code; hence the fact that many programs fail to handle this event, and their windows will become corrupt in this situation.
625:
reserves space for Alpha channel values in its Color Table, however currently this space is not being used to hold any translucency data and is set to zero. By contrast, PNG supports alpha channels in palette entries, enabling semi-transparency in paletted images.
345:
558:: superimposing a given image over a background in such way that some part of the overlapped image obscures the background and the remaining not. Superimposing film/TV titles and credits is a typical application of video overlay.
389:
has sensibility to the three primary colors in different degrees: the more to the green, the less to the blue. So RGB arrangements can take advantage of this by assigning more levels for the green component and fewer to the blue.
485:
and its adaptive palette. Assuming a limited 8-bit depth graphic display, it is necessary to load a given image's adaptive palette into the color hardware registers prior to loading the image surface itself into the
578:, the overlapped image is placed anywhere over the background image, and it is blended in such way that if the pixel color index is the transparent color, the background pixel is kept, otherwise it is replaced.
363:
in a mosaic on screen, the program may not be able to load all the adaptive palettes of every displayed image thumbnail at the same time in the hardware color registers. A solution is to use a unique, common
561:
In the image to be superimposed (indexed color is assumed), a given palette entry plays the role of the transparent color. Usually the index number 0, but other may be chosen if the overlay is performed by
291:
is the set of available colors from which an image can be made. In some systems, the palette is fixed by the hardware design, and in others it is dynamic, typically implemented via a
350:
349:
346:
351:
518:
504:
727:
of the color display's hardware registers, primarily a physical palette, and it is a unique, shared common resource of the system. At boot, it is loaded with the
399:, but this does not leave space in the palette for reserved colors, color indices that the program could use for special purposes. It is more general to use only
348:
256:
511:
851:
439:
525:
381:"in miniature", limiting the possible levels that the red, green, and blue components may have. This kind of arrangement is sometimes referred to as a
633:
images, some video mixing equipment can employ the RGB triplet (0,0,0) (no red, no green, no blue: the darkest shade of black, sometimes referred as
566:. At design time, the transparent color palette entry is assigned to an arbitrary (usually distinctive) color. In the example below, a typical arrow
816:
494:. Here are samples of four different indexed color images with color patches to show their respective (and largely incompatible) adaptive palettes:
237:
645:
software can assume pure white, RGB triplet (255,255,255) from photos and illustrations to be excluded in order to let the text paragraphs
50:
429:
arranged colors plus 16 additional intermediate shades of gray; all images are put together without a significant loss of color accuracy:
608:
347:
825:
686:
are techniques which do not involve the use of palettes nor transparent color at all, but off-image added extra binary data layers.
575:
116:
861:
97:
604:
by hardware. In these cases, the transparent palette entry number is defined by the hardware, and it used to be the number 0.
69:
355:
An adaptive color palette expanding from 2 colors to 256 colors, demonstrating how the image changes (click to see animation)
54:
720:
display modes becomes questionable. These APIs deals with the so-called "system palette" and with many "logical palettes".
517:
735:
palette. Every program can manage freely one or more logical palettes without further expected interference (in advance).
474:
through some algorithm directly from the original image (by picking the most frequent colors). This way, and with further
76:
708:
applications manage the palette of 4-bit or 8-bit indexed color display devices through specialized functions of the
582:
83:
728:
695:
463:
426:
417:
411:
401:
395:
366:
230:
748:
567:
503:
65:
43:
765:
541:
574:
is designed over an orange background, so here the orange areas denoted the transparent areas (left). At
856:
510:
490:. To display different images with different adaptive palettes, they must be loaded one by one, as in a
581:
This technique is used for pointers, in typical 2-D videogames for characters, bullets and so on (the
724:
672:
656:
650:
223:
836:
799:
255:
642:
471:
831:
90:
821:
705:
438:
284:
524:
837:
The RGBQUAD color table entry in BITMAPINFO structure at
Microsoft Developer Network (MSDN)
637:
in this context) as the transparent color. At design time, it is replaced by the so-called
660:
622:
571:
378:
316:
274:
206:
129:
This article is about color lookup tables. For color schemes used in design software, see
134:
377:
This is done by selecting colors in such way that the master palette comprises a full
267:
845:
683:
555:
547:
455:
312:
300:
196:
17:
717:
664:
630:
589:
459:
155:
130:
487:
328:
320:
296:
180:
175:
165:
146:
32:
679:
638:
406:
211:
170:
713:
709:
619:, freely selectable among any of the palette entries used for a given image.
491:
475:
386:
360:
324:
160:
374:, which can be used to display with reasonable accuracy any kind of image.
563:
458:
techniques, real life images are represented with better fidelity to the
731:(mainly a "master palette" which works well enough with most programs).
601:
295:(CLUT), a correspondence table in which selected colors from a certain
784:
597:
482:
343:
323:. Using this technique, 8 bits per pixel are used to describe the
678:
Although related (due to they are used for the same purposes),
425:
sample of a simple mosaic of the four image thumbnails using a
612:
593:
336:
requirement per pixel is lowered from 24 to 8 bits per pixel.
332:
26:
615:
natively support the designation of a given palette entry as
653:
for irregular text arrangement around the image's subjects.
478:, the indexed color image can nearly match the original.
393:
A master palette built this way can be filled with up to
738:
Before the output is effectively made, the program must
273:
The palette used in the image, shown rotating about the
133:. For the UI element also known as utility window, see
585:), video titling and other image mixing applications.
481:
But this creates a heavy dependence between the image
140:
In computer graphics, a finite set of available colors
832:
Color palettes at
Microsoft Developer Network (MSDN)
57:. Unsourced material may be challenged and removed.
311:As of 2019, the most common image colorspace in
421:, which leaves room for some reserved colors.
231:
8:
498:
433:
814:Julio Sanchez and Maria P. Canton (2003).
238:
224:
142:
671:as the transparent color when performing
359:In an application showing many different
117:Learn how and when to remove this message
777:
470:), in which the colors are selected or
188:
145:
181:30-, 36-, or 48-bit color (deep color)
7:
554:color, in order to perform a simple
55:adding citations to reliable sources
712:. The applicability of palettes in
723:The "system palette" is a copy in
25:
852:Computer graphics data structures
800:MSDN. "RGBQUAD Color Table Entry"
667:, can employ the user designated
523:
516:
509:
502:
437:
266:
254:
171:15- or 16-bit color (high color)
31:
42:needs additional citations for
1:
550:image can be designated as a
546:A single palette entry in an
878:
693:
539:
128:
817:The PC Graphics Handbook.
696:List of software palettes
602:full screen video overlay
588:Some early computers, as
427:master palette of 240 RGB
176:24-bit color (true color)
641:. The same way, typical
600:supports sprites and/or
536:Transparency in palettes
66:"Palette" computing
862:Computer output devices
766:List of color palettes
729:default system palette
542:Transparency (graphic)
462:original one by using
356:
319:with 8 bits per pixel
657:2-D painting programs
396:8R×8G×4B = 256 colors
354:
327:level in each of the
785:Handmade Software's
747:triggers a specific
673:cut, copy, and paste
51:improve this article
18:Colour look-up table
607:Some indexed color
468:adaptative palettes
643:desktop publishing
629:When dealing with
609:image file formats
466:(sometimes termed
357:
293:color lookup table
706:Microsoft Windows
701:Microsoft Windows
690:Software palettes
531:
530:
464:adaptive palettes
445:
444:
372:universal palette
352:
285:computer graphics
248:
247:
127:
126:
119:
101:
16:(Redirected from
869:
802:
797:
791:
782:
669:background color
527:
520:
513:
506:
499:
450:Adaptive palette
441:
434:
420:
414:
404:
398:
361:image thumbnails
353:
270:
258:
240:
233:
226:
156:1-bit monochrome
143:
122:
115:
111:
108:
102:
100:
59:
35:
27:
21:
877:
876:
872:
871:
870:
868:
867:
866:
842:
841:
811:
806:
805:
798:
794:
783:
779:
774:
762:
703:
698:
692:
680:image bit masks
661:Microsoft Paint
623:BMP file format
620:
572:pointing device
544:
538:
452:
416:
410:
400:
394:
383:uniform palette
379:RGB color space
344:
342:
317:RGB color model
309:
281:
280:
279:
278:
277:
275:RGB color space
271:
263:
262:
259:
244:
207:RGB color model
161:8-bit grayscale
141:
138:
123:
112:
106:
103:
60:
58:
48:
36:
23:
22:
15:
12:
11:
5:
875:
873:
865:
864:
859:
854:
844:
843:
840:
839:
834:
829:
810:
807:
804:
803:
792:
789:User's Manual.
776:
775:
773:
770:
769:
768:
761:
758:
702:
699:
691:
688:
684:alpha channels
537:
534:
533:
532:
529:
528:
521:
514:
507:
451:
448:
447:
446:
443:
442:
418:6R×7G×6B = 252
412:6R×8G×5B = 240
402:6R×6G×6B = 216
367:master palette
341:
340:Master palette
338:
313:graphics cards
308:
305:
272:
265:
264:
260:
253:
252:
251:
250:
249:
246:
245:
243:
242:
235:
228:
220:
217:
216:
215:
214:
212:Web-safe color
209:
204:
199:
191:
190:
186:
185:
184:
183:
178:
173:
168:
163:
158:
150:
149:
139:
135:Palette window
125:
124:
107:September 2021
39:
37:
30:
24:
14:
13:
10:
9:
6:
4:
3:
2:
874:
863:
860:
858:
855:
853:
850:
849:
847:
838:
835:
833:
830:
827:
826:0-8493-1678-2
823:
819:
818:
813:
812:
808:
801:
796:
793:
790:
788:
787:Image Alchemy
781:
778:
771:
767:
764:
763:
759:
757:
753:
750:
744:
741:
736:
732:
730:
726:
721:
719:
715:
711:
707:
700:
697:
689:
687:
685:
681:
676:
674:
670:
666:
662:
658:
654:
652:
648:
644:
640:
636:
632:
627:
624:
618:
614:
610:
605:
603:
599:
595:
591:
586:
584:
579:
577:
573:
569:
565:
559:
557:
556:video overlay
553:
549:
548:indexed color
543:
535:
526:
522:
519:
515:
512:
508:
505:
501:
500:
497:
496:
495:
493:
489:
484:
479:
477:
473:
469:
465:
461:
457:
456:indexed color
449:
440:
436:
435:
432:
431:
430:
428:
422:
419:
413:
408:
403:
397:
391:
388:
385:. The normal
384:
380:
375:
373:
369:
368:
362:
339:
337:
334:
330:
326:
322:
318:
314:
306:
304:
302:
301:indexed color
298:
294:
290:
286:
276:
269:
257:
241:
236:
234:
229:
227:
222:
221:
219:
218:
213:
210:
208:
205:
203:
200:
198:
197:Indexed color
195:
194:
193:
192:
187:
182:
179:
177:
174:
172:
169:
167:
164:
162:
159:
157:
154:
153:
152:
151:
148:
144:
136:
132:
121:
118:
110:
99:
96:
92:
89:
85:
82:
78:
75:
71:
68: –
67:
63:
62:Find sources:
56:
52:
46:
45:
40:This article
38:
34:
29:
28:
19:
857:Color depths
815:
795:
786:
780:
754:
745:
739:
737:
733:
722:
704:
677:
675:operations.
668:
665:Deluxe Paint
655:
651:bounding box
649:the image's
646:
634:
628:
616:
606:
590:Commodore 64
587:
580:
560:
551:
545:
488:frame buffer
480:
467:
453:
423:
392:
382:
376:
371:
365:
358:
329:RGB channels
310:
292:
288:
282:
261:Sample image
201:
131:color scheme
113:
104:
94:
87:
80:
73:
61:
49:Please help
44:verification
41:
820:CRC Press.
617:transparent
552:transparent
454:When using
405:(as in the
321:color depth
307:Description
297:color space
166:8-bit color
147:Color depth
846:Categories
809:References
694:See also:
639:magic pink
635:superblack
540:See also:
407:Web colors
77:newspapers
718:Truecolor
714:Highcolor
710:Win32 API
647:to invade
631:truecolor
492:slideshow
476:dithering
472:quantized
460:truecolor
387:human eye
325:luminance
760:See also
564:software
303:images.
740:realize
659:, like
583:sprites
576:runtime
568:pointer
409:case),
315:is the
289:palette
202:Palette
189:Related
91:scholar
824:
570:for a
483:pixels
93:
86:
79:
72:
64:
772:Notes
749:event
598:Amiga
98:JSTOR
84:books
822:ISBN
716:and
682:and
663:and
621:The
596:and
287:, a
70:news
725:RAM
613:GIF
611:as
594:MSX
415:or
370:or
333:GIF
283:In
53:by
848::
592:,
828:.
239:e
232:t
225:v
137:.
120:)
114:(
109:)
105:(
95:·
88:·
81:·
74:·
47:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
